In recent years, a so-called micro-machine (MEMS: Micro Electro Mechanical Systems) having various semiconductor elements mounted on a micro-machined Si substrate (silicon wafer) has been developed by using LSI (Large Scale Integration) manufacturing technology, and has become increasingly popular. When manufacturing such a micro-machine, anisotropic etching using an alkaline solution is applied as a microfabrication method of a Si substrate. A small recess with a semiconductor element disposed therein can be formed on the Si substrate by anisotropic etching with good accuracy.
For example, in Patent Literature 1, an LED (light emitting diode) package based on the above mentioned manufacturing technology of the micro-machine is disclosed. The LED package is that a recess (concave portion) with a bottom surface and a lateral surface is formed in a Si substrate, and an LED chip is mounted on the bottom surface of the recess. The recess is formed from the (100) plane of the Si substrate by anisotropic etching. Therefore, the lateral surface of the recess is inclined with respect to the bottom surface of the recess, and includes (111) plane. Further, on the bottom surface and the lateral surface of the recess, an electrode (wiring portion) is formed and electrically connected to the LED chip. A Ti layer and a Cu layer coated on the Si substrate by sputtering are patterned by photolithography and etching to form the electrode, wherein the Si substrate includes the recess. After the electrode is formed, the LED chip is mounted on the bottom surface of the recess, and resin mold (sealing resin) is formed to be filled in the recess, thereby fabricating the LED package.
Herein, during forming the resin mold of the LED package, if the Si substrate is heated for curing the resin mold, temperature strain occurs at both the Si substrate and the resin mold. At this time, the thermal expansion coefficient of the epoxy resin constituting the resin mold is higher than the thermal expansion coefficient of Si constituting the Si substrate, such that the temperature strain occurring on the resin mold is larger than the temperature strain occurring at the Si substrate. Therefore, a warpage occurs at the package due to the difference of the temperature strain between the Si substrate and the resin mold, and there is a risk that the package is poor due to the warpage.